Mechanical face seal

ABSTRACT

A mechanical end face seal comprising two relatively rotatable seal rings, a resilient bellows for providing a secondary seal between one seal ring and either a housing or a rotating shaft and a finger spring element nested in the bellows. The resilient bellows comprises an elastomeric material, such as molded rubber, and has a single convolution having a general cross-sectional shape of an inverted “Omega.” The finger spring member comprises a plurality of generally “U” shaped spring fingers which provide the axial biasing force to urge the ring faces in sealing relation. In a preferred embodiment, the spring includes ferrules for providing radially inward force on a flange portion of each end of the bellows to maintain the secondary seal.

[0001] This application is a continuation-in-part of copendingapplication Ser. No. 09/643,045 filed on Aug. 21, 3100.

[0002] This invention relates to mechanical face seals which provide afluid-tight seal between a housing and a rotatable shaft. Moreparticularly, it relates to such seals that include a finger-type springto provide an axial bias and a secondary seal formed of a rubber orelastomeric bellows.

BACKGROUND OF THE INVENTION

[0003] Seals of the general type are large volume, low cost and areparticularly suitable for use in automotive water pumps. Otherapplications of such seals include other water pumps, such as marinebilge pumps, and pumps for various other liquids.

[0004] Seals currently in common use typically include a primary andmating ring defining relatively rotating sealing faces. These rings maybe made of silicon carbide or carbon. A coil spring provides an axialbias, and an elastomeric or rubber bellows provides a secondary sealbetween the axially movable primary ring and its associated housing orshaft. Examples are found in U.S. Pat. Nos. 4,275,889; 4,779,876 and5,199,719. Similar seals that have a different form of secondary seal orbiasing means are shown in U.S. Pat. Nos. 4,754,981 and 5,947,479.

[0005] Bellows-type seals have enjoyed significant commercial success.Ongoing demand for improved productivity, reliability, durability andchanging envelope requirements within the associated pump dictatecontinued effort for new developments. The present invention representsan advance in seal technology that addresses these needs.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to a mechanical seal assemblywhich utilizes a finger-type spring to provide the axial load upon theaxially movable seal ring. Also, a unique elastomeric bellows isprovided which provides the secondary seal and includes a singleconvolution between its connection to the axially movable seal ring andits connection to the associated housing or shaft.

[0007] The invention comprises, in the broadest form, a mechanical endface seal assembly to provide a fluid tight seal between a housingdefining a bore and a rotatable shaft extending through the bore, theseal assembly comprising an annular mating seal ring, an axially movableannular primary seal ring, the rings each having a seal face in facingrelation to the seal face of the other ring to define a sealinginterface therebetween, a resilient bellows in fluid-tight sealingrelation to the primary ring and adapted to be in fluid-tight sealingrelation to a housing or shaft, the bellows including an inboard web andan outboard web, a base connecting said webs to form a singleconvolution, a finger spring member adapted to urge the primary ringtoward the mating seal ring, the finger spring member including aplurality of spring fingers adapted to be deformed on installation ofsaid seal assembly between the housing and shaft, the finger springbeing nested within the single convolution.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a sectional elevational view of a mechanical face sealassembly, prior to preloading, which embodies the present invention;

[0009]FIG. 2 is a sectional elevational view of the mechanical face sealassembly, shown in FIG. 1, in its installed position and preloadedwithin an illustrative pump;

[0010]FIG. 3 is a side sectional view of the secondary seal bellows ofthe embodiment of FIG. 1;

[0011]FIG. 4 is a plan view of the finger spring member of theembodiment of FIG. 1;

[0012]FIG. 5 is a side elevational sectional view of the finger springmember of the embodiment of FIG. 1, taken approximately along line 5-5of FIG. 4;

[0013]FIG. 6 is a plan view of a form of finger spring member;

[0014]FIG. 6A is a fragmentary plan view of a form of finger springmember;

[0015]FIG. 7 is a sectional elevational view of another embodiment of amechanical face seal assembly, prior to preloading;

[0016]FIG. 8 is a plan view of the mating ring of the embodiment of FIG.7;

[0017]FIG. 9 is a side elevational sectional view of the mating ring ofthe embodiment of FIG. 7, taken approximately along line 9-9 of FIG. 8;

[0018]FIG. 10 is a plan view of the sleeve of the embodiment of FIG. 7;

[0019]FIG. 11 is a side elevational sectional view of the sleeve of theembodiment of FIG. 7, taken approximately along line 11-11 of FIG. 10;and

[0020]FIG. 12 is a sectional elevational view of the mechanical faceseal assembly, shown in FIG. 7, in its installed position and preloaded.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The accompanying drawings, FIGS. 1-5, illustrate one embodimentof a mechanical face seal assembly, generally designated 10, accordingto the present invention. Seal assembly 10 is installed between ahousing 12 having a bore or passage 14 through which a relativelyrotating shaft 16 extends. The seal assembly provides a fluid-tight sealbetween the housing 12 and the relatively rotating shaft 16.

[0022] The housing 12 may be a water pump or other device in which ashaft extends through an aperture in the surrounding housing. It iscontemplated, however, that the seal assembly 10 could have applicationin a wide variety of pumps and other devices, particularly, pumps withsmall diameter shafts. The fluid may be water, or water based, or evenoil.

[0023] The housing of the embodiment illustrated in FIGS. 1 and 2 ispart of a pump, such as a water or other liquid pump, in which animpeller (not shown) rotatable by the shaft 16 elevates the pressure ofthe liquid to be sealed. FIG. 1 shows the seal elements installed on ashaft 16 within a housing 14, but prior to loading the seal rings to apredetermined minimum installed working height, as will be explained.FIG. 2 shows a similar seal in the working position with the springpreloaded. As shown in FIG. 1, the liquid is contained in space 13inboard the housing 12, and the impeller would be disposed to the leftside of seal assembly 10. In describing the illustrated embodiments, theterm “inboard” is used to make reference to the pressure side of thepump and the term “outboard” is used to refer to the ambient environmentexternal to the pump, i.e., the atmosphere. The term “radially inwardly”means toward shaft and “radially outward” means away from the shaft.

[0024] Though shown in cross-section in FIGS. 1, 2, 3 and 5, it shouldbe readily apparent that the seal assembly components are annular, asare the various surfaces of these components which are described indetail.

[0025] As illustrated in FIG. 1, each seal assembly includes a pair ofannular sealing rings including mating ring 18 and primary ring 20associated respectively with shaft 16 and housing 12. These ringsrespectively define mating sealing faces 19 and 21 which are in facing,sealing relation and define a seal interface.

[0026] The sealing rings 18 and 20 are shown as contained in carrierscomprising a cylindrical sleeve 40 and an annular shell or retainer 70.Sleeve 40 includes tubular elongate portion 50 arranged to attach to theshaft 16 to secure the ring 18 for rotation with the shaft 16. Retainer70 includes axially extending cylindrical outer wall portion 72 arrangedto connect the ring 20 to associated housing 12.

[0027] In this embodiment, these latter elements are configured to forma cartridge or unitary seal assembly which may be installed intoposition as a unitary component. It should be understood, however, theinvention does not require that the seal assembly be unitized. Moreover,it is not necessary in every aspect of the invention that a sleeve andretainer be incorporated in the seal assembly. The operative componentsmay be otherwise attached to the housing and shaft in an alternatemanner with the sleeve or retainer or both components eliminated.

[0028] Primary ring 20 is axially movable. It is biased toward ring 18by spring 80, shown in detail in FIGS. 4 and 5, which is a finger-typespring. An elastomeric bellows 100, shown in detail in FIG. 3, providesa fluid-tight secondary seal between ring 20 and the retainer 70. Italso permits axial movement of the ring 20 without affecting thesecondary seal between the ring 20 and retainer 70.

[0029] Referring to FIG. 1, mating ring 18 is fixed axially relative toshaft 16 and housing 12. It includes an annular radial surface 22 spacedaxially inboard from radial sealing face 19, and includes a counterbore17. It also includes an inner cylindrical surface 24 having a largerdiameter than the diameter of the tubular elongate portion 50. The innercylindrical surface 24 is provided with drive notches 28 equally spacedabout the inner periphery of the ring 20. It should be noted that theaxially movable primary ring 20 could be associated with shaft 16, andmating ring 18 could be fixed to housing 12.

[0030] Primary ring 20 includes outboard radial surface 30, spacedoutboard of seal face 21. Ring 20 also includes an inner axialcylindrical surface 32 having a diameter larger than the diameter of thetubular elongate portion 50 of sleeve 40 to permit axial movement of thering. Surface 32 is provided with a plurality of notches 33. Primaryring 20 includes axially extending cylindrical surface 37 that definesits radially outer periphery.

[0031] Referring to FIG. 1, shaft sleeve 40 supports mating ring 18 uponshaft 16. Shaft sleeve 40 includes a tubular elongate portion 50defining inboard enlarged portion 52, shaft engaging portion 54 andoutboard enlarged portion 56. Outboard enlarged portion 56 is sized tofacilitate placement of the seal assembly upon shaft 16 duringinstallation. The axial end of outboard enlarged portion 56 ispreferably swaged outwardly after assembly to retain the curved wallportion 79 of retainer 70, and thus retain the seal as a cartridgebefore installation. Alternatively, outboard enlarged portion 56 mayinclude a plurality of tabs 57 (as shown in phantom in FIG. 2) tomaintain the sleeve 40 and retainer 70 as a unitized seal assembly untilthe seal 10 is installed. Inboard enlarged portion 52 defines aplurality of holes 53 for purposes that will be explained.

[0032] Shaft sleeve 40 defines a seal ring receptacle comprising flange46 which is radial. Shaft sleeve 40 further comprises an annularcylindrical wall 48 and a radial wall 49. Wall 48 is of a diameterlarger than outer cylindrical surface 26 of ring 18. Walls 48 and 49 ofsleeve 40 provide protection for the seal ring 18 against damage fromcontact with other objects, such as other similar seal assemblies whichmay come in contact with each other during handling or storage prior toinstallation. These wall portions may be eliminated or modified in shapewithout departing from the principles of the invention.

[0033] A resilient elastomeric support and secondary seal 60 is moldedonto the inboard enlarged portion 52 of tubular elongate portion 50. Itis mechanically secured to the sleeve 40 during the molding process atholes 53 in the inboard enlarged portion 52.

[0034] Molded support and secondary seal 60 defines an inboard annularbead 61 which engages the outer surface of shaft 16 to provide a sealedrelationship between the shaft 16 and the sleeve 40. Bead 61 alsoassists the metal to metal interference fit between shaft engagingportion 54 of tubular elongate portion 50 and shaft 16, so as tomaintain the axial position of sleeve 40 relative to shaft 16. Bead 61becomes compressed against the shaft, as shown in FIG. 1, wheninstalled.

[0035] Elastomeric support and secondary seal 60 defines a ring seal anddrive portion radially outward of enlarged inboard portion 52 of sleeve40. It includes axial drive portion 62 that extends between enlargedinboard portion 52 and inner cylindrical surface 24 of seal ring 18.Portion 62 defines drive lugs 63 disposed within drive notches 28 formedin inner cylindrical surface 24. This relationship retains the annularseal ring 18 against rotation relative to sleeve 40.

[0036] Elastomeric support and secondary seal 60 further defines anintegrally formed annular seal portion 64 compressed between radial wall46 of sleeve 40 and mating ring 18. It defines radial sealing surface 65in fluid tight contact with ring 18 within counterbore 17.

[0037] The primary ring 20 is supported relative to housing 12 byannular stamped metal primary ring retainer 70. The retainer 70comprises axially extending cylindrical outer wall portion 72, a radialrim 73, a radially extending, annular, outboard portion 74 and anaxially extending generally cylindrical inner wall portion 75.

[0038] The axially extending cylindrical outer wall portion 72 has apredetermined diameter which is received in the bore 14 of housing 12.the housing bore 14 is sized such that the cylindrical portion 72 may bepress-fit into the bore 14 to create a fluid-tight relationship betweenthe retainer 70 and the housing 12. A layer of latex or otherappropriate material may be applied to the outer diameter surface ofwall 71 to ensure a fluid-tight seal between the retainer 70 and thehousing 12. The radial rim 73 seats against a radial surface of the wallof the housing 12 to provide a stop to precisely axially position theretainer 70 relative to the housing 2 and to the shaft 16.

[0039] The generally radial outboard portion 74 defines a radial annularwall portion 76 connecting axially extending cylindrical outer wallportion 72 with an axially extending cylindrical seat wall portion 78.Seat wall portion 78 defines a seat to receive a portion of a bellows100 in fluid-tight relation, as will be explained.

[0040] Generally radial outboard portion 74 further defines a generallyradially extending curved wall portion 79. Radially extending, curvedwall portion 79 connects with axially extending cylindrical inner wallportion 75, sized to be of a diameter larger than tubular elongateportion 50 to permit relative axial movement between sleeve 40 andretainer 70 on installation. Detents 77 formed in cylindrical inner wallportion 75 engage notches 33 in primary ring 20. The inner axial surface32 of primary ring 20 is of a diameter larger than axially extendingcylindrical inner wall portion 75 to permit axial movement of primaryring 20 relative to retainer 70. The inter-engagement between notches 33and detents 77 precludes rotation of the primary ring 20 relative to theretainer 70 which is, in turn, fixed to the housing 12.

[0041] A secondary seal between the primary ring 20 and retainer 70 isprovided by resilient, elastomeric bellows 100. The bellows'cross-section is of a generally inverted “Omega” shape with outboard web102 somewhat longer than inboard web 104. Web portions 102 and 104 arejoined by a radially inner base portion 106 to form a singleconvolution.

[0042] At its radially outer end, inboard web 104 includes an axiallyextending annular flange 108. Flange 108 includes an axially extendingcylindrical surface 110 in fluidtight sealing engagement with axialcylindrical surface 37 of primary ring 20. It also includes a radiallyoutboard cylindrical surface 112 in contact with finger spring 80, aswill be explained in further detail.

[0043] Web 104 includes a radial inboard surface 114 in contact withoutboard radial surface 30 of primary ring 20. It also includes a radialoutboard surface 116 in contact with finger spring 80.

[0044] Outboard web 102 includes an axially extending flange 118. Flange118 includes an axially extending, inner diameter cylindrical surface120 including an inner directed bead 126 in fluid-tight sealingengagement with axial cylindrical seat wall 78 of retainer 70. It alsoincludes a radially outer axially extending surface 122 and a radiallyextending annular surface 124, which contact finger spring 80.

[0045] Referring now to FIGS. 1, 2, 4 and 5, finger spring member 80nested within the single convolution defined by bellows 100 provides theaxial biasing force that causes the primary ring 20 to be urged towardmating ring 18. It includes a ferrule portion 82 associated with theflange 108 at primary ring 20, a ferrule portion 84 associated with theflange 118 at retainer 70. A plurality of spring fingers 86 connectferrule portions 82 and 84. These spring fingers 86 are generally of a“U-shaped” cross-section, with one leg longer than the other.

[0046] Ferrule portion 82 includes a generally cylindrical axiallyextending portion 83 overlying web 108 at surface 112 and a generallyradially extending annular portion 85 adjacent radial outboard surface116 of web 104.

[0047] Ferrule portion 84 includes a generally cylindrical, axiallyextending portion 87 overlying web 118 at surface 122 and a generallyradially extending annular portion 89 adjacent radial inboard surface124 of web 102.

[0048] Each spring finger 86 includes a relatively short radial legportion 92 connected to ferrule 82 at radial annular portion 85 and arelatively long radial leg portion 94 connected to ferrule 84 at radialannular portion 89. The leg portions are joined at a radially inner bendportion 95.

[0049] At its working height, shown in FIG. 2, the seal assemblycomponents are positioned with respect to the housing 12 and shaft 16such that the spring fingers 86 are deformed by movement of the ferruleportions 82, 84 toward each other so that the radial annular portion 85of ferrule 82 is brought toward the radial annular portion 89 of ferrule84, thus placing the finger spring 80 in bending. At this workingheight, the restoring force from bending of fingers 86 causes the radialannular portion 85 to be urged away from the radial annular portion 89,thereby also axially biasing the axially extending annular flange 108and radial outboard surface 116 of inboard radial web 104 inboard fromthe outboard radial web 102. The close contact between inboard surface114 of inboard web 104 and the radial wall 30 of primary ring 20 causesthe primary ring 20 to be biased toward mating ring 18, thus tending tobring the sealing faces 19 and 21 into contact.

[0050] In an operational embodiment for a shaft having a 12 millimeterdiameter, the load on the spring is caused by a working heightcompression of approximately 1 millimeter.

[0051] At the working height, the spring 80 and the elastomeric bellows100 causes the base 106 of bellows 100 to shift in position within theretainer 70 so that the bellows comes into contact with the radiallyextending curved wall portion 79. This is the normal seat position ofthe convolution of elastomeric bellows 100, which still permits someaxial motion of the primary seal ring 20.

[0052] One feature provided by this particular arrangement of theinventive seal embodiment 10 is minimizing the axial and other loads onthe bellows. For example, as the water pump begins operation, the fluidinboard of the elastomeric bellows 100 becomes pressurized to a pressureexceeding the ambient pressure outboard of the seal. This pressure tendsto push at the walls, and especially at the longer radially extendingsurface of inner radial web 104 and of outer radial web 102 and therebytending to deform the shape of the elastomeric bellows.

[0053] One feature provided in this embodiment is that the retainer 70,including the radially extending curved wall portion 79, provide bothaxial and radial support to the elastomeric bellows 100, which, at itscentral base 106 and outboard web 104, takes the shape provided by theretainer 70. The pressure created by the pump impeller therefore cannotdeform the annular shape of the elastomeric bellows and thereby avoidsopening of undesirable leak paths through the secondary seal, forexample, by deforming the squeeze at the axially extending flange 118.

[0054] Although some incidental load on the seal ring 20 may be providedby the bellows 100, one feature of the arrangement is to isolate thebellows 100 from the axial forces acting on the seal. Thus, the primaryfunction of the bellows 100 is to provide a secondary seal between theretainer 70 and the housing 12 and seal ring 20.

[0055] Providing a consistent and efficient secondary seal to thehousing 12 is achieved through squeezing the bellows flange 118 withinthe cup-shaped receptacle defined by the retainer walls 72, 76, 78.Maintaining such a secondary seal creates special difficulties becauseof the pressure differential across the elastomeric bellows seal 100produced during operation of the pump, and also due to the continualvibrational forces created during rotation of the shaft 16 by a motor orother device (not shown), disposed outboard of seal 110.

[0056] One feature of the present invention that facilitates inmaintaining the secondary seal at the outboard end is an annular bead126 centrally disposed on the axially extending surface 120 of flange118. As is best illustrated in FIG. 3, the bead 126 extends inwardly ofthe planar axially extending surface 120. As the flange 118 is fit intothe retainer 70, the bead 126 becomes squeezed against the axiallyextending cylindrical seat wall portion 78, and thereby creating astronger interference fit between the flange 118 and retainer 70. At theinboard end of bellows 100, a secondary seal is formed by flange 108surrounding seal ring 20.

[0057] Ferrule 82 is sized such that it applies a compressive force toaxially extending annular flange 108 of web 104 to establish afluid-tight relationship between the contacting surface of the ferrule82 and flange 108 and the contacting surfaces of the flange 108 andprimary ring 20. Ferrule 84 is sized such that it applies a compressiveforce to axially extending annular flange 118 of web 102 to establish afluid-tight relationship between the contacting surfaces of ferrule 84and flange 118.

[0058] The radial connection of cylindrical axial portion 83 of thefinger spring 80 produces a radially inward force, which, together withthe fluid pressure of the pumped fluid, maintains the secondary seal ofthe flange 108, which is pressed against the primary seal ring 18. Theradially inwardly directed force of the cylindrical axial portion 83 iscapable of maintaining a static seal between axially extendingcylindrical surface 110 of flange 108 and outer diameter axialcylindrical surface 37 of the seal ring 20. For better sealingcapability, cylindrical surface 110 presents a seal at the end of atapered bead-like inner surface of flange 108, as shown, which also issqueezed radially inwardly to maintain the secondary seal against sealring 20. An incidental axial force on the radially exposed wall 109 offlange 108 is countered by the corresponding axially directed oppositepressure force on radially outboard surface 116 and by the spring forceof spring 80 acting axially on the flange 108.

[0059] Proper loading of the seal 10, for example, at a working heightaxial compression of about 1 mm for a seal intended for use with a 12 mmshaft, should ensure that there is no contact between the two radialannular portions 85,89 of ferrules 82,84. A seal for a 12 mm shaft sizetypically may have a “free” height, that is before preloading, as shownin FIG. 1, of about 14.2 mm. After preloading, with conventionalinstruments that measure the distance between the axial ends of seal 10,the typical minimum installed height may be about 13.1 mm.

[0060] Of course, axial motion in the direction tending to further bendthe spring fingers 86 causes the spring force to increase, thus tendingto bias the seal ring 20 against mating ring 18 even more strongly untilthe optimal load is achieved. Axial motion beyond a certain point isimpeded by the contact of the radial annular portions 85,89, but suchcontact must be avoided to prevent an undesirable increase on the loadplaced on seal ring 20. The typical separation between radial annularportions 85,89, under proper loading conditions, will be approximatelyabout 0.5 to 1.0 mm, as shown in FIG. 2.

[0061] It should be noted that in the preloaded state, shown in FIG. 2,the leg of spring finger 86 which connects to ferrule 84 is subject togreater axial deflection than the leg connected to ferrule 82. Thisgreater deflection results from the shape and configuration of the web102, which provides for a separation between the spring finger 86 andwall surface of web 102. This is a preferred configuration because it isdesirable to maintain the shape and configuration as close to square aspossible in order to maintain the support of seal ring 20 and thefluid-tight secondary seal thereagainst. The final configuration of thespring 80 may be formed by one or several stamping steps prior to finalassembly. Special customized stampings are ordinarily required to formthe spring 80, and may be available from commercial precision stampingoperations, such as American Engineered Components of Brighton, Mass.,and Carla Place, N.Y. The finger spring member 80 is made of stainlesssteel and is preferably formed as a single integral component. Thefinger spring member 80 alternatively may be made as separate componentsriveted together or otherwise fastened to each other.

[0062] In a working embodiment, the materials of the elements can bestandard sealing materials. Preferably, the mating ring 18 is made fromsilicon carbide (SiC) and the primary ring 20 may comprise eithersilicon carbide as shown in FIG. 2 or a standard carbon ring, as shownin FIG. 1. The bellows material is resilient and preferably an elastomersuch as molded rubber and the springs 80, including spring fingers 86,are stainless steel or spring steel. The sleeve 40 and retainer 70 arealso stainless steel.

[0063] Dimensions of the elements may vary depending on the shaft sizefor which the seal 10 is intended. As an example, for a shaft size of 12millimeters, the spring 80 may comprise a sheet of 301 or 316L stainlesssteel spring having a thickness of approximately 0.10 to 0.50millimeters, with a preferable thickness of 0.15 millimeter. Thedimensions, and especially the load provided in the free height state,may be critical to the operation of the seal. It is of course importantthat the dimension of the annular elastomeric bellows 100 match thedimensions of the retainer 70 and the seal ring 20 so that theelastomeric portions may be compressed to form the appropriate secondaryseals.

[0064] An alternative configuration of a spring 180 is shown in FIG. 6,in which the ferrule 182,184 provides for additional flexibility in theseal. As shown in FIG. 6, the radial and axial intersection of thespring members 180 may be modified to reduce stiffness in the springforce provided by finger spring member 180. As shown in FIG. 6, variouscuts and gaps in the web of the spring member 180 may be made, whichincrease the flexibility of the spring fingers.

[0065] Radially extending surfaces 185 and 189 of ferrules 182 and 184may be cut adjacent the spring elements 186 so that the spring elementconnections to the ferrules 182, 184 are directly to the correspondingcylindrical axial portions 183, 187 respectively. A gap 194, providedbetween spring element 186 and radial portion 185 and gap 196, may beprovided between spring element 186 and radial annular portion 189 sothat the spring elements extend continuously to cylindrical wallportions 183, so that the spring elements 186 can flex relative to therespective ferrules 182,184 independently of any support derived fromthe radially extending annular members 185 and 189, respectively.

[0066] Additional flexibility may be provided, if desired, by makingadditional cutouts in the ferrules at the comers where the axialcylindrical portions 183, 187 connect to the respective radial annularportions 185, 189. For example, cutouts 197 in the corners of ferrule182 and cutouts 198 in the corners of ferrule 184 provide flexibility inthe movement of the ferrule elements relative to each other and to theweb of the adjacent elastomeric bellows 100, without detracting in anyway from the structural integrity of the finger spring 186. Cutouts197,198 may take any shape, but, as shown, they comprise elongated ovalswhich follow the folds, created during the stamping process, thatcomprise the corners between the axial and radial portions of ferrules182,184.

[0067]FIG. 6A shows a form of spring member 180. Radial portion 185 offerrule 182 is cut to define radial gaps 194 between spring fingerelement 186 and radial portion 185. The spring finger is connected tocylindrical annular portion 183 of ferrule 182. Spring finger leg 194 ofeach spring finger 186 is connected to radial annular portion 189 offerrule 184.

[0068] In the illustration of FIG. 6A, the spring finger legs 192,because of gaps 194, are longer, and somewhat more flexible than theinboard short legs 92 of the embodiment of FIGS. 1-4. The spring rate ofthe finger spring 180 of this illustration is lower than the spring rateof the finger spring 80.

[0069] FIGS. 7-12 illustrate another embodiment of a mechanical faceseal assembly according the present invention.

[0070]FIG. 7 illustrates the mechanical face seal assembly 310 at itsfree height. FIG. 12 shows the seal assembly at its installed or workingheight. The mechanical face seal assembly 310 includes a mating ring 318and a primary ring 320, a sleeve 340, retainer 370, finger spring 380and bellows 400.

[0071] The primary ring 320 of this embodiment is identical to theprimary ring 20 of the first embodiment. Primary ring 320 includesoutboard radial surface 330 and an outer axially extending cylindricalsurface 337. It also includes inner axial cylindrical surface 332defining a plurality of axial notches 333.

[0072] The mating ring 318 of this embodiment is similar to the matingring 18 of the first embodiment. It includes an annular radial backsurface 322. it also includes an inner annular cylindrical surface 324.

[0073] Mating ring 320 does not include drive notches such as notches 28of the embodiment of FIGS. 1-5. It does includes three, approximatelyequally spaced, drive notches 306 defined on the radially outer surfaceof the mating ring 318, as illustrated in FIGS. 8 and 9.

[0074] The rings 318 and 320 are contained in carriers comprisingcylindrical sleeve 340 and annular shell or retainer 370. The sleeve 340of this embodiment illustrated in FIGS. 10 and 11 is similar to thesleeve 40 of the first embodiment. It includes radial flange 346 andouter cylindrical wall 348. Three, approximately equally spaced,radially inwardly dents are defined in the radially outer cylindricalwall 348 of the sleeve 340. Since the sleeve 340 is formed of a thinsheet of metal, a corresponding radially inwardly directed protrusions314 are formed in the annular cylindrical wall 348 . The protrusions 314are located such that they can be situated directly aligned with thedrive notches 306 of the mating ring 318. The protrusions 314 are sizedsuch that they can be received within the drive notches 306 of themating ring 318. The combination of the protrusions 314 of the sleeve340 within the drive notches 306 of the mating ring 318 allows thesleeve 340 to positively engage the mating ring 318 to drive the matingring 318 with the sleeve 340 and the shaft 316 to which the sleeve 340is attached.

[0075] Another difference between the sleeve 340 of this embodiment andthe sleeve 40 of the first embodiment is that the sleeve 340 has a threeslots 319 defined in the radially outwardly extending portion of theflange 346. The slots 319, best seen in FIGS. 10 and 11, areapproximately equally spaced and are located between the protrusions314. The slots 319 of the sleeve 340 permit liquid circulation throughthe sleeve 340. The particular number of slots is not consideredcritical. If necessary, the radial portion of flange 340 could includesix or eight slots separated by webs such as webs 313 shown in FIG. 10.

[0076] A resilient elastomeric support and secondary seal 360 is moldedonto the radially inward and inboard portion of the sleeve 340. Thesupport and secondary seal 360 of this embodiment includes support andsecondary seal elements. Elastomeric support and secondary seal 360defines an integrally formed annular seal portion 364 compressed betweenradial wall 349 and back radial surface 322 of mating ring 318. Anannular seat 362 is positioned within ring 318 and provides radialsupport of the mating ring 318 upon inner annular cylindrical surface324.

[0077] The primary ring 320 is supported relative to housing 312 byannular stamped metal primary ring retainer 370. The retainer 370comprises axially extending cylindrical outer wall portion 372, a radialrim 373, a radially extending, annular, outboard portion 374 and anaxially extending generally cylindrical inner wall portion 375.

[0078] The axially extending cylindrical outer wall portion 372 has apredetermined diameter which is received in the bore314 of housing 312.The housing bore 314 is sized such that the cylindrical portion 372 maybe press-fit into the bore 314 to create a fluidtight relationshipbetween the retainer 370 and the housing 312. A layer of latex or otherappropriate material 371 may be applied to the outer diameter surface ofwall 372 to ensure a fluid-tight seal between the retainer 370 and thehousing 312. The radial rim 373 seats against a radial surface of thewall of the housing 312 to provide a stop to precisely axially positionthe retainer 370 relative to the housing 312 and to the shaft 316.

[0079] The generally radial outboard portion 374 defines a radialannular wall portion 376 connecting axially extending cylindrical outerwall portion 372 with an axially extending cylindrical seat wall portion378. Seat wall portion 378 defines a seat to receive a portion of abellows 400 in fluid-tight relation.

[0080] Generally radial outboard portion 374 further defines a generallyradially extending conical wall portion 379. Conical wall 379 is convexon its outboard surface and concave on its inboard surface adjacentbellows 400.

[0081] A curved wall transition portion 375 a connects the conical wallportion 379 to cylindrical wall portion 375. The cylindrical wallportion 375 extends for a given distance axially and defines detents 377which engage notches 333 on primary ring 320 to retain primary ring 320from rotation relative to sleeve 370, yet permit axial movement.

[0082] Cylindrical wall portion 375 is located radially inwardly of theouter surface of the inner base portion 406 of the bellows 400. Theconical wall portion 379, the curved transition wall portion 375 a andthe cylindrical wall portion 375 are located outboard of the inner base406 of the bellows 400 when the seal assembly is at its free height, asillustrated in FIG. 7.

[0083] As with the first embodiment, a secondary seal between theprimary ring 320 and the retainer 370 is provided by resilientelastomeric bellows 400. The bellows 400 is identical to the bellows 100of the first embodiment. The cross-section of bellows 400 is of agenerally inverted “Omega” shape with outboard web 402 somewhat longerthan inboard web 404. Web portions 402 and 404 are joined by a radiallyinner base portion 406 to form a single convolution.

[0084] At its radially outer end, inboard web 404 includes an axiallyextending annular flange 408. Flange 408 includes an axially extendingcylindrical surface 410 in fluidtight sealing engagement with outeraxial cylindrical surface 337 of primary ring 320. It also includes aradially outboard cylindrical surface 412 in contact with ferrule 382 offinger spring 380.

[0085] Web 404 includes a radial inboard surface 414 in contact withoutboard radial surface 330 of primary ring 320. It also includes aradial outboard surface 416 in contact with finger spring 380.

[0086] Outboard web 402 includes an axially extending flange 418. Flange418 includes an axially extending, inner cylindrical surface 420 influid-tight sealing engagement with an axial cylindrical seat wall 378of retainer 370. It also includes a radially outer axially extendingsurface 422 in contact with ferrule 384 and a radially extending annularsurface 424, which contacts radially annular portion 389 of ferrule 384.

[0087] Finger spring member 380 is nested within the single convolutiondefined by bellows 400 to provide the axial biasing force that causesthe primary ring 320 to be urged toward mating ring 318. It includes aferrule portion 382 associated with the flange 408 at primary ring 320,a ferrule portion 384 associated with the flange 418 at retainer 370. Aplurality of spring fingers 386 connect ferrule portions 382 and 384.These spring fingers 386 are generally of a “U-shaped” cross-section.

[0088] Ferrule portion 382 includes a generally cylindrical axiallyextending portion 383 overlying flange 408 at surface 412 and agenerally radially extending annular portion 385 adjacent radialoutboard surface 416 of web 404.

[0089] Ferrule portion 384 includes a generally cylindrical portion 387overlying flange 418 at surface 422 and a generally radially extendingannular portion 389 adjacent radial inboard surface 424 of web 402.

[0090] Each spring finger 386 includes a relatively short radial legportion 392 connected to ferrule 382, at radially annular portion 385and a relatively long radial leg 394 connected to ferrule 384 at radialannular portion 389. The leg portions are joined at a radially innerbend portion 395.

[0091] Ferrule 382 is sized such that it applies a compressive force toaxially extending annular flange 408 of web 404 to establish afluid-tight relationship between the contacting surfaces of the ferrule382 and flange 408 and the contacting surfaces of the flange 408 withprimary ring 320.

[0092] Ferrule 384 is sized such that it applies a compressive force toaxially extending annular flange 418 of web 402 to establish afluid-tight relationship between the contacting surfaces of ferrule 384and flange 418 and contacting surfaces of flange 418 and axiallyextending seat wall portion 378.

[0093] As with the first embodiment, a finger spring member 380 isnested within the single convolution of the bellows 400 to provide theaxial biasing force that causes the primary ring 320 to be urged towardthe mating ring 318. The finger spring member 380 can be the same asfinger spring members 80 or 180 illustrated in FIGS. 1-6A.

[0094] The retainer 370 is located outboard of the bellows 400 and thefinger spring member 380. The retainer 370 of this embodiment is similarto the retainer 70 of the embodiment of FIGS. 1-5 with the exceptionthat the retainer 370 is shaped to provide for increased axial travel ofthe primary ring 320 and resultant axial compression of the springfingers 386 of finger spring member 380.

[0095] The retainer 370 defines an outboard extending conical wallportion 379. Conical wall 379 is convex on its outboard surface andconcave on its inboard surface adjacent bellows 400.

[0096] A curved wall portion 375 a connects the conical wall portion 379to a cylindrical wall portion 375. The cylindrical wall portion 375extends for a given distance axially and is located radially inwardly ofthe outer surface of the inner base portion 406 of the bellows 400. Theconical wall portion 379, the curved wall portion 375 a and thecylindrical wall portion 375 are located outboard of the inner base 406of the bellows 400 when the seal assembly is at its free height, asillustrated in FIG. 7.

[0097] At its working height, shown in FIG. 12, the spring 380 and theelastomeric bellows 400 cause the inner base portion 406 of the bellows400 to shift in the outboard direction within the retainer 370 so thatthe outboard web 402 of bellows 400 comes into the contact with theconcave conical surface of conical wall portion 379 of the retainer 370.The seal assembly components are positioned such that the spring fingersof spring 380 are compressed axially and provide a restoring force tourge the primary ring 320 into sealing contact with mating ring 318. Thebellows web 402 is placed into contact with the inboard concave surfaceof conical wall 379 of retainer 370. The base 406 defining theconnection between webs 402 and 404 of bellows 400 is displaced axiallytoward the conical wall portion 375 of retainer 370. The bellowsoutboard web 402 is thereby supported upon the concave surface ofconical wall portion 379. Also, the conical shape of portion 379 and thecurved transition wall 375 a and cylindrical wall 375 provide a spacewithin which the bellows 400 and its nested finger spring 380 residewhen the seal 310 is at its operating or working height.

[0098] In the preloaded state, shown in FIG. 12, the leg 394 of springfinger 386 which connects to radial annular portion 389 of ferrule 384is subject to greater axial deflection than the leg 392 connected toferrule 382. This greater deflection results from the shape andconfiguration of the spring and also the radially extending annularsurface 424 on flange 402, which provides for a separation between thespring finger 386 and radial wall surface of web 402.

[0099] Although the invention is described and illustrated with respectto several preferred embodiments, a general understanding of theinvention provides the basis for other modifications and alterationswhich may become readily apparent to a person having ordinary skill inthe art. For example, the preferred embodiments have been described andillustrated in the context of a retainer 70. However, it is consideredpossible to design a seal configuration utilizing a spring arrangementwithout a retainer, in which the bellows arrangement is held in place byfrictional fit against the shaft or housing by a separate attachment(not shown) and to the primary ring by the spring ferrule, such asferrule 82. Elimination of the retainer, and elimination of the sleeve,may be possible while still providing the benefits derived from thefeatures of the present invention. Accordingly, described andillustrated embodiments above are not to be construed as limiting thescope of the invention.

What is claimed is:
 1. A mechanical end face seal assembly to provide afluid tight seal between a housing defining a bore and a rotatable shaftextending through the bore, said seal assembly comprising: an annularmating seal ring; an axially movable annular primary seal ring; saidrings each having a seal face in facing relation to the seal face of theother ring to define a sealing interface therebetween; a resilientbellows in fluid-tight sealing relation to said primary ring and adaptedto be in fluid-tight sealing relation to a housing or shaft; saidbellows including an inboard web and an outboard web; a base connectingsaid webs to form a single convolution, a finger spring member adaptedto urge said primary ring toward said mating seal ring, said fingerspring member including a plurality of spring fingers adapted to bedeformed on installation of said seal assembly between the housing andshaft; said finger spring being nested within said single convolution.2. A mechanical end face seal assembly as claimed in claim 1 whereinsaid finger spring includes a plurality of generally U-shaped springfingers having an inboard leg and an outboard leg adapted to be deformedon installation of said seal assembly between the housing and shaft. 3.A mechanical end face seal assembly as claimed in claim 2 wherein saidwebs of said bellows are generally radial and parallel to each other andsaid outboard radial web is longer than said inboard radial web, andsaid legs of said spring fingers are generally parallel to each otherand said outboard leg is longer than said inboard leg.
 4. A mechanicalend face seal assembly as claimed in claim 2 wherein said inboard radialweb of said bellows includes an axially extending annular flange influidtight sealing engagement with said axially movable primary ring,and said outboard radial web includes an axially extending annularflange and wherein said finger spring includes a ferrule connected tosaid inboard legs of said spring fingers, said ferrule being associatedwith said axially extending annular flange of said inboard web of saidbellows, said finger spring further including a ferrule connected tosaid outboard legs of said spring fingers, said ferrule being associatedwith said axially extending annular flange on said outboard web of saidbellows.
 5. A mechanical end face seal assembly as claimed in claim 3wherein said inboard radial web of said bellows includes an axiallyextending annular flange in fluidtight sealing engagement with saidaxially movable primary ring, and said outboard radial web includes anaxially extending annular flange and wherein said finger spring includesa ferrule connected to said inboard legs of said spring fingers, saidferrule being associated with said axially extending annular flange ofsaid inboard web of said bellows, said finger spring further including aferrule connected to said outboard legs of said spring fingers, saidferrule being associated with said axially extending annular flange onsaid outboard web of said bellows.
 6. A mechanical end face sealassembly as claimed in claim 4 wherein each said ferrule includes acylindrical axially extending portion overlying said axially extendingannular flange of one of said webs and a radially extending annularportion adjacent said web, the leg portions of said spring fingers beingconnected to said ferrules at said one of said cylindrical axiallyextending portion and said radially extending annular portion of saidferrules.
 7. A mechanical end face seal assembly as claimed in claim 5wherein each said ferrule includes a cylindrical axially extendingportion overlying said axially extending annular flange of one of saidwebs and a radially extending annular portion adjacent said web, the legportions of said spring fingers being connected to said ferrules at saidone of said cylindrical axially extending portion and said radiallyextending annular portion of said ferrules.
 8. A mechanical end faceseal assembly as claimed in claim 6 wherein the radially extendingannular portion of said ferrule associated with said axially extendingannular flange of said inboard web of said bellows defines slotsseparating said radially extending annular portion of said ferrule fromsaid inboard legs of said spring fingers.
 9. A mechanical end face sealassembly as claimed in claim 7 wherein the radially extending annularportion of said ferrule associated with said axially extending annularflange of said inboard web of said bellows defines slots separating saidradially extending annular portion of said ferrule from said inboardlegs of said spring fingers.
 10. A mechanical end face seal assembly asclaimed in claim 8 wherein the radially extending annular portion ofsaid ferrule associated with said axially extending annular flange ofsaid outboard web of said bellows defines slots separating said radiallyextending annular portion of said ferrule from said outboard legs ofsaid spring fingers.
 11. A mechanical end face seal assembly as claimedin claim 9 wherein the radially extending annular portion of saidferrule associated with said axially extending annular flange of saidoutboard web of said bellows defines slots separating said radiallyextending annular portion of said ferrule from said outboard legs ofsaid spring fingers.
 12. A mechanical end face seal assembly as claimedin claim 6 wherein said inboard legs of said spring fingers areconnected only to said cylindrical axially extending portion of saidferrule associated with said axially extending annular flange of saidinboard radial web of said bellows and said outboard legs of said springfingers are connected to said radially extending annular portion of saidferrule associated with said axially extending annular flange of saidoutboard radial web of said bellows.
 13. A mechanical end face sealassembly as claimed in claim 6 wherein said axially extending flange onsaid outboard web of said bellows includes a radial inboard surface incontact with the radially extending annular portion of said ferruleassociated with said flange of said outboard web to position saidoutboard legs of said spring fingers in spaced relation to said outboardweb of said bellows.
 14. A mechanical end face seal assembly as claimedin claim 12 wherein said axially extending flange on said outboard webof said bellows includes a radial inboard surface in contact with theradially extending annular portion of said ferrule associated with saidflange of said outboard web to position said outboard legs of saidspring fingers in spaced relation to said outboard web of said bellows.15. A mechanical end face seal assembly as claimed in claim 13 whereinon deformation of said spring fingers, said outboard legs of said springfingers are subject to greater deflection than said inboard legs.
 16. Amechanical end face seal assembly as claimed in claim 14 wherein ondeformation of said spring fingers, said outboard legs of said springfingers are subject to greater deflection than said inboard legs.
 17. Amechanical end face seal assembly as claimed in claim 6 wherein saidcylindrical axially extending portions of said ferrules apply radialcompressive forces to said axially extending annular flanges of saidwebs.
 18. A mechanical end face seal assembly as claimed in claim 12wherein said cylindrical axially extending portions of said ferrulesapply radial compressive forces to said axially extending annularflanges of said webs.
 19. A mechanical end face seal assembly as claimedin claim 4 wherein said assembly includes a retainer to support saidaxially movable primary ring relative to the housing or shaft, saidretainer including a cylindrical seat wall portion, and said axiallyextending flange of said outboard radial web is in fluid-tight sealingengagement with said axial cylindrical seal wall of said retainer.
 20. Amechanical end face seal assembly as claimed in claim 12 wherein saidassembly includes a retainer to support said axially movable primaryring relative to the housing or shaft, said retainer including acylindrical seat wall portion, and said axially extending flange of saidoutboard radial web is in fluid-tight sealing engagement with said axialcylindrical seal wall of said retainer.
 21. A mechanical end face sealassembly as claimed in claim 19 wherein said retainer includes agenerally radially extending curved wall portion, said curved wallportion adapted to support the outboard web of said bellows.
 22. Amechanical end face seal assembly as claimed in claim 20 wherein saidretainer includes a generally radially extending curved wall portion,said curved wall portion adapted to support the outboard web of saidbellows.
 23. A mechanical end face seal assembly as claimed in claim 19wherein said retainer includes a generally radially extending conicalwall portion having an inboard concave surface to support the outboardweb of said bellows.
 24. A mechanical end face seal assembly as claimedin claim 20 wherein said retainer includes a generally radiallyextending conical wall portion having an inboard concave surface tosupport the outboard web of said bellows.
 25. A mechanical end face sealassembly as claimed in claim 19 wherein said axially extending annularflange on said outboard web includes an inner directed bead in sealingengagement with said cylindrical seat wall portion of said retainer. 26.A mechanical end face seal assembly as claimed in claim 20 wherein saidaxially extending annular flange on said outboard web includes an innerdirected bead in sealing engagement with said cylindrical seat wallportion of said retainer.
 27. A mechanical end face seal assembly asclaimed in claim 4 wherein said assembly includes a retainer to supportsaid axially movable primary ring relative to the housing or shaft, andsaid retainer includes a generally radially extending conical wallportion having an inboard concave surface to support the outboard web ofsaid bellows.
 28. A mechanical end face seal assembly as claimed inclaim 6 wherein said assembly includes a retainer to support saidaxially movable primary ring relative to the housing or shaft, and saidretainer includes a generally radially extending conical wall portionhaving an inboard concave surface to support the outboard web of saidbellows.
 29. A mechanical end face seal assembly as claimed in claim 12wherein said assembly includes a retainer to support said axiallymovable primary ring relative to the housing or shaft, and said retainerincludes a generally radially extending conical wall portion having aninboard concave surface to support the outboard web of said bellows. 30.A mechanical end face seal assembly as claimed in claim 13 wherein saidassembly includes a retainer to support said axially movable primaryring relative to the housing or shaft, and said retainer includes agenerally radially extending conical wall portion having an inboardconcave surface to support the outboard web of said bellows.
 31. Amechanical end face seal assembly as claimed in claim 15 wherein saidassembly includes a retainer to support said axially movable primaryring relative to the housing or shaft, and said retainer includes agenerally radially extending conical wall portion having an inboardconcave surface to support the outboard web of said bellows.
 32. Amechanical end face seal assembly as claimed in claim 17 wherein saidassembly includes a retainer to support said axially movable primaryring relative to the housing or shaft, and said retainer includes agenerally radially extending conical wall portion having an inboardconcave surface to support the outboard web of said bellows.
 33. Amechanical end face seal assembly as claimed in claim 2 wherein saidassembly includes a sleeve, said sleeve including a resilient supportand secondary seal molded thereto, said molded support and secondaryseal is in fluid-tight contact with said mating ring.
 34. A mechanicalend face seal assembly as claimed in claim 19 wherein said assemblyincludes a sleeve, said sleeve including a resilient support andsecondary seal molded thereto, said molded support and secondary seal isin fluid-tight contact with said mating ring.
 35. A mechanical end faceseal assembly as claimed in claim 33 wherein said molded resilientsupport and secondary seal includes an annular bead to seal said sleeveto said shaft.
 36. A mechanical end face seal assembly as claimed inclaim 34 wherein said molded resilient support and secondary sealincludes an annular bead to seal said sleeve to said shaft and saidretainer is adapted to connect said primary ring to said housing.
 37. Amechanical end face seal assembly as claimed in claim 33 wherein saidmating ring includes drive notches and said molded support and secondaryseal includes drive lugs engaging said drive notches.
 38. A mechanicalend face seal assembly as claimed in claim 34 wherein said mating ringincludes drive notches and said molded support and secondary sealincludes drive lugs engaging said drive notches.
 39. A mechanical endface seal assembly as claimed in claim 33 wherein said mating ringincludes drive notches and said sleeve includes drive dents engagingsaid drive notches of said mating ring and said resilient support andsecondary seal includes an annular seat positioned within said matingring to provide radial support therefor.
 40. A mechanical end face sealassembly as claimed in claim 34 wherein said mating ring includes drivenotches and said sleeve includes drive dents engaging said drive notchesof said mating ring and said resilient support and secondary sealincludes an annular seat positioned within said mating ring to provideradial support therefor.
 41. A mechanical end face seal assembled asclaimed in claim 33 wherein said sleeve and retainer are interconnectedto form a cartridge.
 42. A mechanical end face seal assembled as claimedin claim 34 wherein said sleeve and retainer are interconnected to forma cartridge.
 43. A mechanical end face seal assembled as claimed inclaim 40 wherein said sleeve and retainer are interconnected to form acartridge.
 44. A mechanical end face seal as claimed in claim 2 whereinsaid spring is made of stainless steel and said bellows is an elastomer.45. A mechanical end face seal as claimed in claim 6 wherein said springis made of stainless steel and said bellows is an elastomer.
 46. Amechanical end face seal as claimed in claim 12 wherein said spring ismade of stainless steel and said bellows is an elastomer.
 47. Amechanical end face seal as claimed in claim 13 wherein said spring ismade of stainless steel and said bellows is an elastomer.
 48. Amechanical end face seal as claimed in claim 40 wherein said spring ismade of stainless steel and said bellows is an elastomer.